A new study suggests that Mars had an oxygen-rich environment long ago -- even before Earth.

Oxford University researchers, led by Professor Bernard Wood of Oxford University's Department of Earth Sciences, compared meteorites and surface rocks before coming to this conclusion.

The team studied meteorites from Mars and rocks found by NASA's Spirit rover on Mars' surface. They found that the surface rocks were five times richer in nickel than the meteorites.

They believe this is the case because of subduction, where material is recycled into the planet's interior. The study says that Mars' surface was oxidized long ago, and through subduction, materials rich in oxygen went into the planet's interior and were recycled back to the surface about 4000 million years ago. Earth didn't experience a rise in atmospheric oxygen until 2500 million years ago.

The meteorites, though, are younger rocks that came from deep within the red planet. Hence, they are unphased by this subduction.

"What we have shown is that both meteorites and surface volcanic rocks are consistent with similar origins in the deep interior of Mars but that the surface rocks come from a more oxygen-rich environment, probably caused by recycling of oxygen-rich materials into the interior," said Wood. "This result is surprising because while the meteorites are geologically 'young', around 180 million to 1400 million years old, the Spirit rover was analysing a very old part of Mars, more than 3700 million years old."

Spirit, a golf cart-sized, solar-powered robot geologist that was sent to Mars in 2004, spent six long years traveling the Martian surface. But after enduring many harsh winters on Mars, Spirit finally fell silent in 2010, and was removed from the mission in mid-2011.

NASA has been relying on rover Curiosity to dig up new info on the red planet now. It landed on Mars in August 2012, and has found rock samples that suggest life on Mars and questionable radiation levels that could determine human travel to Mars.

quote: The team studied meteorites from Mars and rocks found by NASA's Spirit rover on Mars' surface. They found that the surface rocks were five times richer in nickel than the meteorites.

The problem I have with this is the earth doesn't lots of uniform rocks, it has the exact opposite: rocks all over the place with totally different content. As far as I can tell it's just about impossible to say these rocks aren't from here, and since it is far more likely that the "meteorites" were rocks ejected from volcanoes on earth than they were bits of the Martian terrain thrown into space by some massive meteor hitting Mars, then to call them Martian Meteors is wrong.To me the most important point about these Martian Rovers is they are the forerunners of sending people, and the most obvious point that seems to be overlooked is sending people to a seriously lifeless place based upon poor information and wrong assumptions can only really have one logical outcome: death.While we have just managed to send people to the surface of the moon, the fact is that was really a piece of cake in terms of space exploration.

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